Manhole lift insert with frangible positioner

ABSTRACT

A manhole lift insert with a socket portion and a frangible portion that is inserted in a pre-positioned bushing in the outer wall of a manhole form. A key in the sleeve portion may be received in a keyway in the bushing in the form wall so that the insert is properly oriented in the form.

This application relates to and claims the benefit of U.S. ProvisionalApplication No. 60/483,414, filed Jun. 26, 2003 and entitled “ManholeLift Insert With Frangible Positioner”, which is hereby incorporated inits entirety by this reference.

FIELD OF THE INVENTION

This invention relates to manhole lift inserts and devices forpositioning such inserts in concrete molds used to form manholes andother pre-cast concrete products.

BACKGROUND OF THE INVENTION

Pre-cast concrete manholes are widely used throughout the world toprovide access to storm and sanitary sewer systems and a variety ofother below-ground installations of piping, cables and the like. Manholelifts are eye bolt-like devices 10 illustrated in FIGS. 1 and 2 that arepositioned within a lift insert 12 imbedded in concrete 50 that forms amanhole or other precast concrete product. Manhole lift 10 permits theattachment of chains and other devices to lift a pre-cast concreteproduct in order to transport it and ultimately position it where it isto be used. Two lifts and corresponding lift inserts are typically usedper manhole, for example. The lift inserts are placed at the same heightat opposite positions on the outer surface of the manhole.

Lift inserts 12 can have a bayonet-type socket, and lifts 10 can havebayonet-type bases formed by two opposed ears 16 on the lift shaft 18that are received in opposed grooves 20 in insert 12. After lift 10 isfully inserted in insert 12, it is rotated one quarter turn, as shown inFIG. 2, to lock it in place so that it will not withdraw from insert 12.

Prior devices for holding insert 12 in position within a manhole form orother pre-cast concrete product form have utilized expensive, relativelycomplex devices with a spring loaded shaft having a bayonet base thatlocks within the bayonet socket in an insert. A rubber molding assemblythat fits within the lift insert and has a nut and bolt inside theassembly as described in U.S. Pat. No. 6,109,587 has also been used. Theexpense, complexity and other problems associated with such devices makeit desirable to have a simpler, easier to use device for holding a liftinsert 12 in position during the concrete casting process.

SUMMARY OF THE INVENTION

Embodiments of the present invention include a lift insert with a socketportion and a frangible portion that is inserted in a pre-positionedbushing associated with the outer wall of a manhole form. A key on thefrangible portion may be received in a keyway in the bushing so that theinsert is properly oriented in the form. Concrete is then poured intothe form, enveloping and affixing the socket portion within the manholewall.

The lift insert is manufactured of plastic or other suitable materials.A weakened, frangible region is provided on the frangible portion in aposition immediately adjacent to the form wall so that after theconcrete is cured, the manhole and form can simply be separated, causingthe socket portion, which is embedded in the concrete, to separate fromthe frangible portion in the bushing. Nothing needs to be removed beforeseparating the form and cured manhole, with a consequent diminution innecessary labor by simplification of the lift insert insertion processand elimination of the need to remove a hole-forming component or aseparate positioning component before separating the cured manhole andthe form.

Accordingly, it is an object of various embodiments of the presentinvention to provide a lift insert for a manhole form or other pre-castconcrete product form that is capable of being positioned and held inplace in a relatively inexpensive manner.

Another object of various embodiments of the present invention is toprovide a lift insert for a manhole form or other pre-cast concreteproduct form having a frangible portion used to position the insert inthe form in which the frangible portion automatically separates from asocket portion of the lift insert when the form is separated from theconcrete product.

Other objects, features, and advantages of the present invention willbecome apparent with reference to the remainder of the written portionand the drawings of this application, which are intended to exemplifyand not to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a manhole and a lift insertpositioned in concrete.

FIG. 2 is a perspective view showing the externally visible portion ofthe lift insert imbedded in concrete with a lift locked within theinsert.

FIG. 3 is an exploded perspective view of a fragment of the outer formwall of a pre-cast concrete manhole form with the bushing and liftinsert according to an embodiment of the present invention.

FIG. 4 is a top plan view of the frangible insert according to anotherembodiment of the present invention shown positioned in a portion of amanhole wall surrounded by a manhole form and insert-receiving bushing,with the form, bushing and wall shown in section.

FIG. 5 is a section view taken along line 5-5 in FIG. 4.

FIG. 6 is an axial view taken from the open end of a lift insertaccording to another embodiment of the present invention with the insertreceiving bushing shown in broken lines.

FIG. 7 is an enlarged view of the portion of FIG. 5 in circle 7.

FIG. 8 is a top schematic view of a handle useable with a frangibleinsert according to certain aspects and embodiments of the presentinvention.

FIG. 9 is a side schematic view of the handle of FIG. 8.

FIG. 10 is a perspective view of the handle of FIG. 8.

FIG. 11 is a perspective view of a lift insert according to anotherembodiment of the present invention.

FIG. 12 is a schematic view of a frangible joiner according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 3 illustrates a lift insert 110 in accordance with the presentinvention. Insert 110 is shown prior to insertion in bushing 112 locatedon outside surface 114 of outer wall 116 of concrete form 117. Concreteform 117 also has inner form wall 118 (shown in FIG. 4).

Insert 110 has two principle portions, socket 12 and frangible member130. Socket 12 forms hole 38 (shown in FIGS. 4 and 5) in which a lift isreceived. Frangible member 130 is received within bushing 112 of form117. Socket 12 is attached to frangible member 130 along a frangibleregion 132 that may be best understood by reference to FIG. 7. FIG. 7illustrates that frangible region 132 is a portion of insert 110 havinga very thin wall created by an annular v-shaped groove defined by acollar 134 attached to socket 12 and an adjacent thin region 136 offrangible member 130. Socket 12 may be separated from frangible member130 at frangible region 132 by applying a shearing stress to thefrangible region.

In the embodiment shown in FIG. 3, collar 134 allows frangible member130 to be positioned within bushing 112 to a desired depth, therebyensuring that frangible portion 132 is positioned such that removal ofouter wall 116 from the completed manhole will fracture insert 110 atfrangible portion 132. Thus, collar 134 may be any structure whichprevents insert 110 from being inserted into bushing 112 to some pointbeyond frangible region 132, such as a bulges, tabs, or otherobstructive protuberances. In some embodiments, the lift insert 110 maybe used without a bushing 112, rather the insert 110 may be positionedin the outer wall 116 by itself. In such an embodiment, collar 134 maybe adapted to contact the outer wall 116 to position the insert 110 at adesired depth.

The collar can be located at other positions other than the oneillustrated in FIG. 3. For example, a collar 204 can be located in aposition as shown in FIG. 11. In embodiments that include a collar 204located in the position shown in FIG. 11, lift insert 110 may beinserted into a bushing such that collar 204 contacts the bushing tolocate the lift insert 110 at an appropriate depth with respect to theconcrete form. In the embodiment shown in FIG. 11, socket end of theinsert is inserted through the bushing until the collar 204 on thefrangible member 130 contacts the bushing.

Socket 12 and frangible member 130 need not be formed in one piece, butmay be manufactured separately and joined thereafter by some readilyfrangible, fracturable or deformable connector. For example, a frangiblejoiner 300, such as an inner insert or coupling may be provided. Asshown in FIG. 12, the frangible joiner 300 may simply be a relativelythin, cylindrical insert. Frangible member 130 and socket 12 may beslipped over opposite ends of the joiner 300 so that they abut in aconfiguration similar to that shown in the figures. Such a couplingwould thereby hold frangible member 130 and socket 12 in the desiredorientation for the manhole forming process but could be thin enough tofracture in the same manner as frangible region 132 or deform enough topermit separation of socket 12 from frangible member 130. In anotheralternative, frangible member 130 could be bonded to socket 12 in amanner that will fail, permitting the socket 12 easily to separate fromfrangible member 130.

Appropriate rotational positioning of insert 110 is achieved by use of akeyway 138 in each bushing 112. Keyway 138 receives key 140, which ispositioned on the outside of frangible member 130. Keyway 138 may be alongitudinal slot on the inside of bushing 112, or, as illustrated inthe figures, a longitudinal slot remaining after removing of an entirelongitudinal wall section in a tubular bushing 112.

Key 140 in sleeve 130 may be an upstanding ridge or projection. Such akey 140 may be provided, as is illustrated in the figures, bypositioning on the outside of sleeve 130 two side-by-side upstandingprojections 144, which may be a structure superior to a solid keybecause projections 144 can bend slightly towards each other toaccommodate narrow keyways 138. In an alternative not shown, sleeve 130may include a keyway that corresponds to a ridge in bushing 112. In someembodiments, such as the embodiment shown in FIG. 11, the key 140 maynot extend the entire length of the frangible member 130.

Frangible member 130 is generally cylindrical, although other shapes maybe selected as appropriate. For example, frangible member 130 may beoval in shape to further ensure it is properly aligned when inserted inbushing 112. The outside of sleeve 130 may also be provided withlongitudinal ribs 146 that contact bushing 112. Longitudinal ribs 146lend frangible member 130 sufficient flexibility to ensure thatfrangible member 130 can compress if necessary to accommodate a narrowbushing 112, while providing sufficient friction to firmly secure insert110 in place when concrete is poured into form 117. Ends 150 of ribs 146and key 140 may be tapered to facilitate insertion of sleeve 130 inholes 152 in wall 116 of form 117 with which holes 152 and bushings 112are aligned.

Referring to FIG. 3, the keyway 138 of bushing 112 is oriented such thatthe position of the socket portion ensures that the lift can bepositioned correctly. As show in FIG. 2, the lift is inserted so thatits eye portion is vertical.

In the embodiment shown in FIG. 3, insert 110 is positioned by insertingfrangible member 130 through a hole 152 and into bushing 112 from theinterior surface 154 of wall 116. In other embodiments, such as theembodiment shown in FIG. 11, the insert may be inserted through thebushing from an outer wall of the form. Next, in the embodiments shownin FIGS. 3 and 11, the insert 110 is rotationally positioned so that itskey 140 will be received in the keyway 138, and the frangible member 130is pressed into the bushing 112 until collar 134 abuts either the wall116 or the bushing 112 so that when concrete 50 is placed between formwalls 116 and 118 and allowed to cure, frangible region 132 ispositioned at about the interface between cured concrete 50 and theinterior surface 154 of outer wall 116. Form walls 116 and 118 are thenremoved, thereby causing each insert 110 to separate along frangibleregion 132 without the need for removal of any hole forming sockets.Frangible member 130 will typically remain within bushing 112 and may beeasily pushed out from either side as, for instance, by pressing a newinsert 110 into bushing 112.

In other embodiments, such as the embodiments shown in FIGS. 8-10, abushing 200 may be incorporated into a handle 202 to facilitatepositioning an insert. Handle 202 may be attached in a removable mannerto an outer surface of a concrete form prior to insertion of the insert.Curved slots 206 in the handle 202 may facilitate securing the handle ina removable manner to the outer surface of the concrete form by a pairof screws or other appropriate structures. Hand grips 208 allow thehandle to be rotated such that the screws or other appropriate fastenersare engaged by the curved slots 206. Handle 202 may be disengaged fromthe screws or other appropriate fasteners by rotating the handle in theopposite direction.

As will be readily appreciated by those skilled in the art, frangibleinserts may be advantageously manufactured by molding them of plastic,such as any of a variety of a thermoplastic resins, including polyvinylchloride (PVC), and other suitable materials such as other plastics orsteel.

As those skilled in the art will appreciate, the particular embodimentof this invention described above and illustrated in the figures isprovided for explaining the invention, and various alterations may bemade in the structure and materials of the illustrated embodimentwithout departing from the spirit and scope of the invention asdescribed above.

1. A frangible manhole lift insert, comprising: (a) a socket, whereinthe socket comprises a hole at a first end, the hole adapted to receiveand retain a lift in a releasable manner; (b) a frangible member, thefrangible member adapted to be located at least partially in an apertureformed in a form wall, the frangible member joined to the socketproximate to the first end of the socket at a frangible region, whereinapplying a shearing stress proximate to the frangible region separatesthe socket from the frangible member.
 2. The frangible manhole liftinsert of claim 1, wherein the frangible member further comprises aplurality of ribs extending from an outer surface of the frangiblemember.
 3. The frangible manhole lift insert of claim 2, wherein theplurality of ribs are oriented substantially parallel to one another. 4.The frangible manhole lift insert of claim 3, wherein the plurality ofribs are oriented substantially parallel to a longitudinal axis of thesocket.
 5. The frangible manhole lift insert of claim 1, wherein themember further comprises a key extending from the outer surface of thefrangible member, the key adapted to interact with a keyway associatedwith the form to orient the socket in a desired orientation.
 6. Thefrangible manhole lift insert of claim 5, wherein the key is adapted tointeract with a keyway in a bushing associated with the aperture in theform wall.
 7. The frangible manhole lift insert of claim 1, wherein thesocket and frangible member are formed as a single piece.
 8. Thefrangible manhole lift insert of claim 1, wherein the socket andfrangible member are formed as two separate pieces and wherein afrangible joiner joins the two pieces together.
 9. The frangible manholelift insert of claim 1, wherein the lift insert further comprises acollar extending from a portion of the frangible member.
 10. Thefrangible manhole lift insert of claim 9, wherein the collar extendsfrom a portion of the frangible member proximate to the socket.
 11. Thefrangible manhole lift insert of claim 9, wherein the collar extendsfrom a portion of the frangible member distal to the socket.
 12. Amethod of including a lift insert in a concrete structure in a desiredlocation and orientation, comprising: (a) providing a concrete form, theconcrete form comprising at least a first form wall and a second formwall, interior surfaces of the first and second form walls oriented withrespect to one another to define a void, the first form wall furtherdefining at least one aperture; (b) locating a frangible insert in thefirst form wall aperture such that a frangible region of the insert isproximate the interior surface of the first form wall; (c) depositing aquantity of casting material into the void; (d) allowing the castingmaterial to cure; and (e) removing the form walls from the cured castingmaterial such that a portion of the frangible insert shears off toexpose a socket portion of the frangible insert, the socket portiondefining a hole at a first end, the hole adapted to secure a lift in areleasing manner.
 13. The method of including a lift insert in aconcrete structure in a desired location and orientation of claim 12,further comprising locating a bushing in the first form wall aperture,the bushing interacting with portions of the frangible insert to locatethe frangible insert in a desired location and orientation with respectto the first form wall.
 14. The method of including a lift insert in aconcrete structure in a desired location and orientation of claim 13,wherein locating the bushing in the first form wall aperture furthercomprises locating the bushing in the first form wall aperture such thata keyway of the bushing is located to interact with a key on thefrangible insert to orient the frangible insert in a desired manner.